Oil cracking unit



June 10, 1947- N.` o. HARMON OIL CRACKING UNIT Filed May 15, 1946 'n Il IN V EN TOR.

BVI

Manna/1111 HeP/a/v Patented June 10, 1947 l UNITED STATES PATENT OFFICE 2,421,880 oIL CRACKING UNIT Nathaniel O. Harmon, Los Angeles, Calif. Application May 15, 1946, Serial No. 669,893

15 Claims. 1

This invention has to do with improvements in oil cracking apparatus of the general type comprising a heating tube through which a flow of oil is maintained under condition permitting variation or control of the thickness of the oil lm or stream undergoing cracking. The present application is a continuation in part of my copending application Ser. No. 585,085, filed March 27, 1945, on Apparatus and process for treating hydrocarbon oil.

My primary object is to provide for accurate and positive control of the thickness of that portion of an oi1 stream passing through a cracking tube, which is subjected to cracking temperatures by a heating medium applied to the exterior of the tube. Particularly the in vention aims to permit definite predetermination of .the oi1 stream thickness by the formation of walls dening the oil conducting space at the inside and outside of the stream, and providing for variation of the transverse dimensions of the space, and therefore of the oil stream, by relative transverse adjustment of the confining walls.

In accordance with the invention, I provide within an externally heated cracking tube an elongated member, preferably in the form of a smaller diameter tube, mounted for transverse or vertical adjustment within and relative to the outer tube. Desirably the oil flow may be limited to the lower portion of the space between the tubes, which space by reason of the adjustability of the inner member, is variable in accordance with the character of the charging stock to correspondingly vary and control the thickness of the oil stream being subjected to cracking temperature. In this manner I assure highly e'icient, rapid and uniform heating of the oil stream, with resultant accomplishment of higher oi1 conversion and less carbon formation than otherwise could ibe obtainable with less eiiicient heating, or with such systems as permit localized or excessive over-heating of the oil.

Further in the interests of maintaining maximum heat transfer rates, I preferably employ as the heating medium a molten normally solid material such as lead, or any other suitable metal or salt capable of circulation in molten condition. Constant circulation of for example molten lead, is maintained along the outside of the outer tube, preferably through a jacket confining the heating medium to that lower portion of the tube corresponding to the oi1 depth. f

Various additional features and aspects of the invention might preliminarily be recited at length, but all these, as well as the objects referred to in the foregoing, will be more readily understood from the following detailed descrip- .tion of a typical embodiment of the invention shown by the accompanying drawing, in which:

Fig. 1 is a verticalcross-sectional view taken longitudinally through the cracking unit;

Fig. 2 is a fragmentary cross-section online 2-2 of Fig. 1; and

Fig. 3 is a similar View illustrating the variational form of the invention.

While in Fig. 1 I have shown a single cracking unit, it will be understood that a cracking plant may employ any number of such units interconnected for series or parallel iiow of the oil through them, depending upon the nature and purposes of the process. Since the invention is primarily concerned with the features of construction in the unit itself, the showing of a single unit will suffice for present purposes.

The unit, generally indicated at l0, is shown to comprise an outer horizontally extending tube II terminally connected, as by threaded joints III, with enlarged chambers I2 and I2a of corresponding form and construction. Each chamber may include a body section I3 attached to the pipe II, and a removable cover section I4 attached to the body by screws I5.l Charging stock to be cracked, is introduced to chamber I2 through the inlet line I6, the oil thence passing through tube II wherein it is subjected to cracking and partial vaporization, the unvaporized residue being withdrawn from chamber I'2a through the outlet line Il. Vapors are removed from either or both of the chambers through lines I8. Preferably the tube assembly will be inclined toward the right sufficiently to maintain gravity oil flow therethrough at the desired rate.

Tube I I contains a member I9, which in the broad contemplation of the invention may be of any suitable shape and construction capable of being adjustably mounted to extend longitudinally within and in spaced relation to the outer tube, in a manner permitting variation of the transverse dimensions of the oil passing space between the member and tube, and to correspondingly vary the transverse dimensions of the oil film or stream undergoing cracking. Preferably, member I9 comprises a tube 20, vertically alined with the tube I I and spaced therefrom to provide an oil passage or channel 22. Tube 20 may be supported in minimum spaced relation to the outer tube II by screws 23 threaded into the inner tube and secured by nuts 23a, the screws having their heads bearing against the bottom portions of tube II as best shown in Fig. 2. The top of the tube optionally may contain apertures 2|, through which access may be had to the nuts 23a. The screws 23 are adjustable to vary the tube clearance at 22 and therefore the thickness of the oil stream or lm passing between the tubes from chamber I2 into chamber I2a. At this point it may be mentioned that the invention contemplates maintaining the oil flow at a rate such that the oil streamwill: occupy space. 22 toalevel approximately atthe horizontal axial plane of the outer tube II.

Provision also is made for vertically adjusting. the ends of the tube 20 in accordance with the. spacing to be maintained at 22, by suitableA means,

generally indicated at 23|, operablev at the out` Typally.,

sides of the chambers I2 and I2a. each adjustment may comprise anarm 24J projecting from the closed end of the tubefandsup-F ported on an eccentric 24'I carried by shaft 25 extending outwardly through an appropriate` seal gland 26. Arm 2.4.' may be conned against such lateral movement as. might otherwise. shiftthe tube Ztl' out of' vertical alinementwithtube. I Iby guide iianges 2l' cast integrally with the chamber covers I4 andpositioned' at eachY side ofthe eccentric 2.4"I". Upon rotation of` shaft 2'5,` as by tool. applied to its outer end; 28, eccentric 2'4'IL is rotated to raise or lower the arm 24; and' therefore the corresponding endA of' tube 26'. AsA will be understood, the eccentric 241: and screws 23 may be designed toY provide for any desired'. minimum clearance at 22 between the tubes, and to permit any predetermined enlargement ofy that clearance.

T ube I'I- is externally heated,- preferably by a continuous flow of heating Huid confined to the lower portion of the tube corresponding gener.- ally to the oil depth therein. Thus the. tube is Shown in Fis. 2v to carry a weldedjacket Z9. ex.- tending substantially the length. of the. tube. between the connections at II`. may be passed' longitudinally in either directionthrough the jacket, by way ofV its. terminal pipe connections 3U and' 31|. which lead; to, and: from. a.

heater, not Shown, from whicna continuouscirculation. of the heating medium may be main.- tained. In View of the importance of maintain,-

ing themaximurn ratesof. heat transfer fromthe. heating fluid in thejacket 29. tothe wall of. thev tubef I.I, L preferably employ. as;the heating. me dium, a molten, normally solid. material such. as` lead' or a compound containingiusible metallicsalts.

For purposes. of. most, eflicient. operation,` the space at 22 is adjusted to reduce the transverse. dimension or thickness of. the oill stream flowing therethrough, toa degree assuring rapidw anduni-` form transference of. heat iromthe tube wall I I toallfportionsof theoil. stream. Inthis manner I= avoid4 excessiveor. localized over-heating of the. oil. by assuring its rapid.. and.. uniform heating`v to aclosely controllable temperature productive of maximum. conversion with. minimum. carbon formation. The. vaporized constituents of, the oil flow throughl the. space in. the. upper interior ofiA tube. II` into the chambersv I2 and I2a., and. the; unvaporized residuum entering chamber. I.2a,.is1 continuously withdrawn through. its outlet Il.

Fig. 3 illustrates atvariationalforrn' of theinevention in which theouter tubev 34 andA heating iiuid jacket 35.1'1ave essentially the same form. as the previously described corresponding parts, but with theshape of the inner member or tube3- changedfromthecircular formof tube-2|l.Y Here The heating ii'uid.

tube 36 is shown to have a cylindrical or circular cross-section lower portion 36a, concentric with the tube 34, and an upper arcuate portion 36h, the curvature of which normally affords somewhat greater clearance at 31 than in the oil passing space 38 below the tube. Because of the concentricity of tube 34 and the lower portion 36a of the inner tube in the position shown, greater uniformity may be maintained throughout the oil, passing clearance at 38 between the tubes. As will be understood, the same provisionsmay be made for eiecting vertical adjustments of the tube 36, as previously explained in connection with tube in the rst described form.

Oil or vapor condensate are accessible to the interior' of tube, 2li', as through openings 2I, and provision may be made for maintaining liquid drainage from theA lower end of the tube, as through` opening 40 discharging into chamber I2a.

I claim:

1. An oil cracking unit comprising an elon.- gated tubeg. means for externally heating. said. tube, a member. extending longitudinally insidey said tube and spaced' therefrom, means for pass.- ingY oil through the space between said member and tube, and` means mounting saidv member for adjustment to. vary the transverse dimensions of. saidspace.

2; An oil cracking unit comprising an elongated tube, means for externally heating said tube, a hollow tubular member extending longitudinally inside said tube and spaced' therefrom.. means for passing oil through the space between said member and tube, and means mounting said member for adjustment to vary thev transverse dimensions of said space.

3. An oil cracking unit comprising an elongated tube, means for externally heating; said. tube, a member extending longitudinally inside said tube and'. spaced therefrom, means for. pass.- ing oil through the space between said4 member andv tube, and adjustable means for varying-I the position of said member laterally within the tube to vary the transverse dimension of. said. space..

4'. Arr oil cracking unit comprising an elon gated' tube, means for externally heating. said. tube, a member extending longitudinally inside. said tube and spaced` therefrom, means ior pass-- ing oil through the space between said. member and tubeand. adjustable means beyond. one end of the tube for varying the position ofsaid mem ber. laterally within the tube to. vary the trans` verse. dimensions.. of said space.

5. An oil cracking unit comprising an. elongated tube; means. f orexternally heating1 said. tube, a member extending longitudinally inside; said tubey and spaced.. therefrom, means. for pass-- ing oil: through the space between. said member and. tube, and. adjustable. means beyond. both,y ends of` the tube for varying. the position of saidzmember laterally within the'tubeftor varythe trans.-Y verse dimensions` of said space.

6. An oil cracking unit. comprising arr elongated tube,. means` for externally heating saidtube, a member extending longitudinally.v inside said tube and. spaced therefrom, meansffor passing oil. through the space between. said' member and tube, and adjustable means inside the tube: for varying the positionof' saidt member laterally within the tube to vary' the'transversedi. mensiors of said space.

7. An oil cracking unitl comprising, an elongated tube, means for externally applying; heating fluid to the lower portion only* of the' tube;

a member extending longitudinally inside said tube and spaced therefrom, means for passing oil through the space between said member and tube, and means mounting said member for adjustment to vary the transverse dimensions of said space.

8. An oil cracking unit comprising an elongated tube, a heat conducting fluid jacket carried by the lower portion only of the tube, a member extending longitudinally inside said tube and spaced therefrom, means for passing oil through the space between said member and tube, and means mounting said member for adjustment to vary the transverse dimensions of said space.

9. An oil cracking unit comprising an elongated tube, means for passing molten normally solid heating liquid longitudinally along the outside of said tube, a member extending longitudinally inside said tube and spaced therefrom,

means for passing oil through the space between said member and tube, and means mounting said member for adjustment to vary the transverse dimensions of said space.

10. An oil cracking unit comprising an elongated horizontally extending tube, chambers connected to the ends of said tube, means for externally heating said tube, a hollow tubular member extending longitudinally inside said tube and spaced therefrom, means for passing oil from one of said chambers through the space between said member and tube into the other of said chambers, means for removing vapors from one of said chambers, and means mounting said member for adjustment vertically within said tube to vary the spacing of the member from the bottom portion of the tube.

l1. An oil cracking unit comprising an elongated horizontally extending tube, chambers connected to the ends of said tube, means for externally heating said tube, a hollow tubular member extending longitudinally inside said tube and spaced therefrom, means for passing oil from one of said chambers through the space between said member and tube into the other of said chambers, means vertically supporting said member within the tube, means for removing vapors from one of said chambers, and means mounting said member for adjustment vertically within said tube to vary the spacing of the member from the bottom portion of the tube.

12. An oil cracking unit comprising an elongated horizontally extending tube, chambers connected to the ends of said tube, means for externally heating said tube, a hollow tubular member extending longitudinally inside said tube and 6 spaced therefrom, means for passing oil from one of said chambers through the space between said member and tube into the other of said chambers, means for removing vapors from one of said chambers, and means cooperable with an end portion of said member within one of the chambers Y for adjusting the positionof said member vertically within the tube.

13. An oil cracking unit comprising an elongated horizontally extending tube, chambers connected to the ends of said tube, means for externally heating said tube, a hollow tubular member extending longitudinally inside said tube and spaced therefrom, means for passing oil from one of said chambers through the space between said member and tube into the other of said chambers, means for removing vapors from one of said chambers, and means cooperable with an end portion of said member within one of the chambers and operable from the outside thereof to adjust the position of said member vertically within the chamber.

14. An oil cracking unit comprising -an elongated horizontally extending tube, chambers connected to the ends of said tube, a heat conducting lluid jacket carried by the lower portion only of the tube, a hollow tubular member extending longitudinally inside said tube and spaced therefrom, means for passing oil from one of said chambers through the space between said member and tube into the other of said chambers, means for removing vapors from one of said chambers, and means cooperable with an end portion of said member within one of the chambers and operable from `the outside thereof to adjust-the position of said member vertically within the chamber.

15. An oil cracking unit comprising an elongated horizontally extending tube, chambers connected to the ends of said tube, means for externally heating said tube, a hollow tubular member extending longitudinally inside said tube and spaced therefrom, means for passing oil from one of said chambers through the space between said member and tube into the other of said chambers, means for removing vapors from one of said chambers, said member having end projections extending into said chambers, and adjustable means extending through the chamber walls and cooperable with said end projections to adjust said member vertically within the tube to vary the spacing of the member from the bottom portion of the tube, said adjustable means being operable at the outsides of the chambers.

NATI-IANIEL O; HARMON. 

